Biological assessment


INDIRECT IMPACTS-APPALACHIAN ELKTOE



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INDIRECT IMPACTS-APPALACHIAN ELKTOE

  1. Disruption of Fish Host Migration


The temporary causeways at the Cane River and South Toe River are not expected to cause significant disruptions of fish migration patterns, thus the dispersal of the Appalachian elktoe is not expected to be adversely impacted.

        1. Cane River and South Toe River


Given the small size, 500 ft2 (47 m2), of the proposed causeway at the Cane River crossing, significant disruptions to fish migrations are not anticipated at this site. At the South Toe River crossing causeways are needed for demolition of the existing structure and construction of the new structure. The impacts (temporary fill) from causeways total 9,600 ft2 (892 m2). Given the large amount of river bed impacted by causeway construction, temporary disruption of fish migration is likely to occur at this site. The partial width causeway design, which insures that at least 50% of the river channel will remain open during the life of the causeways, will help to minimize disruptions to fish migrations. Because the causeways are temporary, they are not expected to permanently interfere with normal migration of any fish species in the South Toe River.

Temporary disruptions to the normal migration of individuals of some fish species may occur while the causeways are constructed and in place. Individual fish may be restricted, or deterred from swimming upstream of the causeways; however, these temporary disruptions to the fish behavior are not expected to significantly affect the survival of transforming Appalachian elktoe as there is ample habitat downstream of the causeways for transformed mussels. Additionally, temporary restriction of individual fish from habitat upstream of the causeways will not impact the distribution of the Appalachian elktoe upstream of the causeway impact areas, as all of the identified potential fish host species that occur in the Cane River and South Toe River, are widely distributed throughout the respective rivers. Quantifying the impacts of the causeways on glochidia transformation would be very difficult, and require intensive fish sampling and examination. Such an analysis may also have more of an adverse impact on Appalachian elktoe glochidia than the actual impacts of fish migration disruption that may occur from the causeways.


        1. Tributaries


The effects of culverts on fish passage are well documented (Bagget et al. 2001, Moser and Terra 1999, Carey and Wagner 1996). Many of the stream crossings along the project alignment are proposed to be extensions of existing structures. Although the design of the culverts incorporates measures that reduce the potential for impacts, some of these culverts may still act as barriers to some fish species. However, these potential barriers to fish migration are not expected to result in adverse impacts to the Appalachian elktoe, because the tributaries that may contain barriers do not provide habitat for the Appalachian elktoe for reasons other than the presence of culverts or pipes (too small, high gradient etc.).

      1. Potential for Toxic Spills


Hazardous Spill Basins will be constructed adjacent to the Cane River and South Toe River crossings. The roadway will be configured such that any spill runoff will be directed through the facility (basin) to interrupt the flow and provide temporary storage until it can be properly removed. This will prevent any hazardous material from entering the rivers in these locations. With the elimination of direct discharge at the Cane River and South Toe River crossings and the installation of Hazardous Spill Basins in these locations, the proposed project will reduce the potential threat of impacts of toxic spills along the roadway.

      1. Indirect Effects on Land Use


The proposed project will improve access to future I-26 and I-40 and provide new construction and expansion opportunities for businesses. Highway-oriented commercial development is anticipated near the US 19 and future I-26 inter-change (NCDOT 2001) as well as within or adjacent to Burnsville, and Spruce Pine where sewer and water services exist, or are planned (NCDOT 2007). Although slight declines in the permanent population has occurred in the project study areas in recent years, additional new growth that is likely to occur may be related to second home and retiree development and the associated tourism sectors of the economy, as the number of new home starts has grown in recent years (NCDOT 2007).

Yancey County and the town of Burnsville have a Land Development Plan adopted in 2001, which directs intensive urban development away from environmentally sensitive areas and promotes cluster development adjacent to US 19/19E, where existing, or proposed sewer and water services exist and some development already exists (NCDOT 2007). Yancey County does not have a zoning ordinance, but does implement a watershed water supply protection ordinance through its building permits and inspections office (NCDOT 2007). There are no formal land use plans in place for Mitchell County, or the town of Spruce Pine; however, Spruce Pine does have a zoning ordinance enforced by the Mitchell County Department of Inspections (NCDOT 2007). Despite the fact that a zoning ordinance is in place, local officials in Burnsville indicate that special permits and variances are commonly requested and granted (HNTB North Carolina 2004).

The project is consistent with regional goals to improve business access to interstate highways and to enhance tourist access to resort areas. Vegetated medians will be used along the roadway to be consistent with the goal to keep US 19E visually attractive (NCDOT 2001). The land use plans and zoning ordinances discourage strip commercial development along the corridor (NCDOT 2007). The proposed project will benefit the region and community by making travel more efficient, increasing traffic carrying capacity, and improving safety (NCDOT 2001).

Yancey County experienced a 15.3% population growth from 1990-2000, compared to 3.2% from 1980-1990.Mitchell County experienced lower growth rates between these decades: 0.1% from 1980-1990 to 8.6% from 1990-2000. The 16.2% growth rate of the Demographic Area studied in the Qualitative Indirect and Cumulative Effects Assessment (ICE) for this project is higher than the overall growth rates of the respective counties, suggesting that development patterns in these counties is largely occurring along the US 19/US 19E corridor. However, these growth rates are still less than the 21.4% statewide increase during the period from 1990-2000 (HNTB North Carolina 2004).

The difference in growth rate of Yancey County compared to that of North Carolina appears to be due in part to distance from interstate highways and large metropolitan areas, the shortage of easily developable lands in the Appalachian region, and limited water and sewer services. However, development pressures do exist within this region. Tourism, an increasingly important part of the local economy is assisting the market for second home development. Regionally, the proposed improvements to US 19E, in combination with other area projects, will strengthen the link between the Asheville and Boone areas and will make the area more accessible to a greater number of tourists, enhance truck access to I-26 and I‑40, and shorten the commute to metropolitan Asheville (NCDOT 2001).

Tourist-oriented businesses which provide goods and services for through travelers would likely locate along US 19E, where both water and sewer services are available or proposed. This could result in linear sprawl, with associated congestion and safety concerns. The use of medians with the proposed improvement should minimize this possibility (NCDOT 2001).

The 2004 ICE analysis for this project (HNTB North Carolina 2004) identified a Potential Growth Impact Area (PGIA) of approximately 2.0 miles on either side of the existing roadway. Within the PGIA, areas with “High Potential” and “Medium Potential for Impact” are identified. The areas with the highest potential for impacts are at the western terminus of the project with I-26 in Madison County, within the town of Burnsville and at the eastern terminus of the US19 E widening in Spruce Pine. The 2007 ICE likewise recognized the western terminus of the project, and the cities of Burnsville and Spruce Pine as having the highest potential for induced growth, because these areas have, or are proposed to have sewer and water service infrastructure. Development within unincorporated areas outside of these three identified areas is expected to continue at historic rates and patterns due to constraints associated with lack of sewer and water services, steep topography, and other natural constraints (NCDOT 2007).

Accounting for meanders and direction of flow (running parallel to the road), approximately 10 river miles (RM) (16 river kilometers) of the Cane River, 6.5 RM (10.5 river kilometers) of the South Toe River and 3.5 RM (5.6 river kilometers) of the North Toe River occur within the PGIA. The majority of the river reaches within the PGIA are occupied by the Appalachian elktoe. Additionally, the entire reach of the South Toe River in the PGIA is designated Critical Habitat, as well as approximately 1.25 miles (2.01 kilometers) of the North Toe River and 0.25 miles (0.4 kilometers) of the Cane River within the PGIA. The PGIA/ICE Study Area is depicted in relationship to Critical Habitat in Figure 2.

Recent development trends in Yancey County indicate that upscale residential communities of second homes and small scale commercial uses (HNTB North Carolina 2004) are becoming more prevalent (NCDOT 2007). Additionally, the improved roadway may make commuting to areas outside of the demographic area more attractive bringing new permanent residents to the area. This effect diminishes from west to east as the distance from Asheville, the regions largest employment center increases (NCDOT 2007). The amount of induced development will vary along the corridor, but will most likely be greatest within areas that are currently, or proposed to be, serviced by water and sewer.

The 2004 ICE study concludes that project construction may induce small-scale development of this nature mainly within 1-2 miles (1.6-3.2 kilometers) of the US 19E corridor. The 2007 ICE study also identifies small-scale induced development potential in this corridor; however, the role of the proposed roadway in contributing to this development is shown to be minimal (NCDOT 2007).

Substantial industrial development is not considered likely due to the steep topography of the area. Local officials; however, have stated that there are some available industrial sites and that “the communities have a desire to grow the manufacturing employment base” and are hopeful that the improved accessibility provided by the widened roadway will encourage future development to locate in the area (HNTB North Carolina 2004). There are no known plans for any redevelopment of the closed industrial and manufacturing facilities, or new plants for future manufacturing (NCDOT 2007). Small, tourist-related industries are more likely to locate in this area than large-scale industry. The highest potential for this type of impacts occurs within the cities of Burnsville and Spruce Pine. A “Medium Potential for Impact” was identified in the 2004 ICE study in areas along the Cane River for a distance of approximately 5 RM (8 kilometers), along the South Toe River for a distance of approximately 2 RM (3.2 kilometers), and along NC 80 from US 19E in Newdale north to the crossing of the North Toe River. These three river segments are currently occupied by the Appalachian elktoe. Two of these reaches, the South Toe River and the North Toe River, are Designated Critical Habitat.

The various probable induced land-use impacts discussed above can potentially result in adverse impacts to the Appalachian elktoe and it’s Designated Critical Habitat. As discussed above, the most likely induced land use impact is small-scale residential community and commercial developments. Development activities like those above can result in various adverse impacts to water quality, such as sedimentation/erosion while the sites are being developed, increased storm-water impacts from an overall increase in impervious surface area, and the potential for increases in point source and non-point source pollution as the population expands and the watershed is developed. Future residential developments and future businesses may propose new sites for wastewater discharge or tap into existing facilities, all of which would result in an increase in the amount of wastewater discharge into the watershed. There is currently a proposal to develop a wastewater discharge facility in the South Toe River, in part to meet projected expansion goals (See Cumulative Impacts Section 6.3)



Although the proposed roadway is expected to contribute to some induced land-use impacts, this influence is minimal compared to the effect that water and sewer services will have (NCDOT 2007). The land suitability development potential within the identified ICE study area was analyzed under 1) existing conditions, 2) No-Build (R-2518/R-2519) scenario, 3) Future Build 1 (R-2518/R-2519) scenario along with water and sewer infrastructure improvements and 4) Future Build 2 (R-2518/R-2519) with a higher weighting factor for the proposed roadway improvements. The results of this GIS model indicate that potential for induced development in the ICE study area is mainly due to the expansion of water and sewer services, and the overall projected growth with the project build is only slightly higher than under a No-Build scenario (NCDOT 2007). While large-scale development of the area is not anticipated to occur, and thus large-scale water quality degradation is not expected throughout the Nolichucky River Basin, the anticipated small-scale development activities can cause localized water quality impacts, which in turn could result in adverse impacts to the Appalachian elktoe and its’ Designated Critical Habitat. This is especially true in areas which lack development controls. Quantifying the degree of indirect water quality degradation is difficult to project and will be dependent on the location of the future development activities, the amount of impervious surface area associated with future development and any stormwater and buffer controls that are put in place.

        1. Impervious Surface Area

As discussed in Section 4.2.3.1, impervious surface areas can result in adverse effects to water quality. Multiple studies have demonstrated that water quality and stream ecosystem degradation begins to occur in watersheds that have approximately 10% coverage by impervious surfaces (Stewart et al. 2000, Schueler 1994, Arnold and Gibbons 1996 and others). The NCWRC recommendations for management of protected aquatic species watersheds are to limit imperviousness to 6% of the watershed (NCWRC 2002).
The construction of the proposed project will result in an increase of 5,180,562.44 ft2 (118.929 acres or 481,290 m2) of impervious surface area with the additional road lanes. However, only 3,867,365.38 ft2 (88.64 acres or 359,290 m2) occur within the portions of the project(s) draining to occupied Appalachian elktoe habitat or designated Critical Habitat. Future development in the respective watersheds within the project action area(s) will also result in an increase in impervious surface area in the form of rooftops, driveways, parking lots etc. Land development trends indicate that there was little change in the level of imperviousness, which is around 5.1% within the ICE study area from 1986-2001 (NCDOT 2007).
Further examination using the 2001 Land Cover data of the three subbasins of concern to the Appalachian elktoe was conducted by Earth Tech (Earth Tech 2007):

“The North Toe River has 5.5 percent imperviousness. The North Toe Basin contains 16,810 acres, of which 918 were impervious surface acres. In order for the basin to reach six percent imperviousness an additional 91 acres of impervious surface would need to be built. Because of the coefficient or multiplier, this would be equivalent to 676 acres of low intensity residential, 311 acres of high intensity residential, or 186 acres of commercial/industrial land uses, or some combination thereof. The development of 676 acres of low intensity residential would represent a 41 percent increase over 2001 development levels. Likewise the 311 acres of high intensity residential would be a 93 percent increase and the 186 acres represents a 144 percent increase in commercial/industrial land uses.

The South Toe Basin contains 17,708 acres, of which 929 were calculated to be impervious surface acres (5.2 percent imperviousness). In order for the basin to reach six percent imperviousness an additional 134 acres of impervious surface would need to be built or the equivalent of 998 acres of low intensity residential, 459 acres of high intensity residential, or 275 acres of commercial/industrial land uses. The development of 998 acres of low intensity residential would represent a 53 percent increase over 2001 development levels. The 459 acres of high intensity residential would be a 180 percent increase and the 275 acres represents a 333 percent increase in commercial/industrial land uses.

The Cane River Basin contains 24,943 acres, of which 1,235 were impervious surface acres (4.9 percent imperviousness). In order for the basin to reach six percent imperviousness, an additional 263 acres of impervious surface would need to be built or the equivalent of 1,959 acres of low intensity residential, 902 acres of high intensity residential, or 539 acres of commercial/industrial land uses. The development of 1,959 acres of low intensity residential would represent a 91 percent increase over 2001 development levels. The 902 acres of high intensity residential would be a 435 percent increase and the 539 acres represents a 726 percent increase in commercial/industrial land uses” (Earth Tech 2007).

Caution should be taken with regard to how the percent imperviousness numbers are used and compared with the 6 percent threshold number recommended by NCWRC without knowing how that threshold number has been derived or calculated. The methodology used by Earth Tech “assigned a coefficient or multiplier to each land cover type. Therefore, even undeveloped land generated a certain amount of impervious surface acreage to the overall percentage. In our analysis, due to the large percentage of undeveloped land within the drainage basin, all non-development land covers (forested, pasture, etc.) generated approximately 3.2 percent imperviousness to the total percent imperviousness within the basin. Unless the threshold number was generated using a similar methodology a comparison of percent imperviousness may not be valid” (Earth Tech 2007).



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